There are several similar-subject threads, But I feel this is specific enough that it deserves it's own thread, due to its recent popularity.
The trend for off-road is to get the motor out of the rear wheel (LMX, LR big block, Raptors new mid drive), but for whatever reason, when someone wants a high-powered E-bike for the street, the large rear Direct-Drive (DD) hubmotors remain popular (Cromotor, MXUS, Crown, 35mm-40mm width stator hubs that have been ventilated/oil-cooled, etc).
These hubs are heavy, so...trying to save a few ounces by using a bicycle rim is being seen less and less. (I also recommend full-suspension at any speeds over 30-MPH / 48 kph, due to pothole hits).
There are benefits to using a higher voltage and a fast Kv of motor, and then mounting the hub in a smaller diameter rim. Due to the way that bicycle vs moped tires and rims are measured, a 16-inch moped tire/rim is very similar to 20-inch bicycle tire/rim (2.25 – 16 moped tire has a 20.5″ OD). A 19-inch moped rim/tire is similar to a 24-inch bicycle. Motorcycle / moped tires are very durable and flat-resistant, where bicycle tires are usually lighter for a given width of tire.
The problem that has drawn more builders to moped rims lately is that...heavy-duty bicycle rims have a limit to how much of an angle the spoke nipples can have when they are seated in their rim-holes. It is very desirable to have at least a one-cross pattern to the spokes, as opposed to a radial pattern.
Moped tires can be easily and cheaply found in widths as narrow as 2.25, to over 3.0-inches. Here is a link with a lot of info on moped tires/rims: http://www.myronsmopeds.com/category/parts/tires/
From ES member Kent,
left: Yescom hub (28mm wide stator) in 26-inch bicycle rim/tire, 19 lbs / 8.6 kg
right: Crystalyte H35 (35m wide stator) in 19-inch moped rim/tire, 28 lbs / 12.7 kg
Mattyciii's rim, showing how the spoke holes are angled on his rim, allowing the spokes to be at a much bigger angle than a bicycle rim.
For those builders who are interested in this, I hope for this thread to become a collection of links to parts that have proven successful.
As an example, the Kinaye Motorsports bike uses a: Hutchinson GP1 17" x 2.25" street tire, outside diameter is 21.5". The rim is a 17" X 1.6" moped. If you like this, but don't want to build one yourself, John Rob Holmes has built many of these.
edit: from ES member relanium. The pic below is a 16-inch moped rim, and that is the smallest size I would recommend. With tire mounted I believe the outside diameter of the tire is 20.5-inches. Motor is the MXUS-3000, with the common spoke flange ERD of 231mm.
"19 inch moto rims vs 26 inch bicycle wheels" (38 pages)
http://endless-sphere.com/forums/viewtopic.php?f=2&t=55458
"16/17/18/19 inch rims," 7-pages, JRH
http://endless-sphere.com/forums/viewtopic.php?f=31&t=35442
"Using 17/19 inch moped rims on large hubmotors"
http://endless-sphere.com/forums/viewtopic.php?f=2&t=69104
The trend for off-road is to get the motor out of the rear wheel (LMX, LR big block, Raptors new mid drive), but for whatever reason, when someone wants a high-powered E-bike for the street, the large rear Direct-Drive (DD) hubmotors remain popular (Cromotor, MXUS, Crown, 35mm-40mm width stator hubs that have been ventilated/oil-cooled, etc).
These hubs are heavy, so...trying to save a few ounces by using a bicycle rim is being seen less and less. (I also recommend full-suspension at any speeds over 30-MPH / 48 kph, due to pothole hits).
There are benefits to using a higher voltage and a fast Kv of motor, and then mounting the hub in a smaller diameter rim. Due to the way that bicycle vs moped tires and rims are measured, a 16-inch moped tire/rim is very similar to 20-inch bicycle tire/rim (2.25 – 16 moped tire has a 20.5″ OD). A 19-inch moped rim/tire is similar to a 24-inch bicycle. Motorcycle / moped tires are very durable and flat-resistant, where bicycle tires are usually lighter for a given width of tire.
The problem that has drawn more builders to moped rims lately is that...heavy-duty bicycle rims have a limit to how much of an angle the spoke nipples can have when they are seated in their rim-holes. It is very desirable to have at least a one-cross pattern to the spokes, as opposed to a radial pattern.
Moped tires can be easily and cheaply found in widths as narrow as 2.25, to over 3.0-inches. Here is a link with a lot of info on moped tires/rims: http://www.myronsmopeds.com/category/parts/tires/
From ES member Kent,
left: Yescom hub (28mm wide stator) in 26-inch bicycle rim/tire, 19 lbs / 8.6 kg
right: Crystalyte H35 (35m wide stator) in 19-inch moped rim/tire, 28 lbs / 12.7 kg
Mattyciii's rim, showing how the spoke holes are angled on his rim, allowing the spokes to be at a much bigger angle than a bicycle rim.
For those builders who are interested in this, I hope for this thread to become a collection of links to parts that have proven successful.
As an example, the Kinaye Motorsports bike uses a: Hutchinson GP1 17" x 2.25" street tire, outside diameter is 21.5". The rim is a 17" X 1.6" moped. If you like this, but don't want to build one yourself, John Rob Holmes has built many of these.
edit: from ES member relanium. The pic below is a 16-inch moped rim, and that is the smallest size I would recommend. With tire mounted I believe the outside diameter of the tire is 20.5-inches. Motor is the MXUS-3000, with the common spoke flange ERD of 231mm.
"19 inch moto rims vs 26 inch bicycle wheels" (38 pages)
http://endless-sphere.com/forums/viewtopic.php?f=2&t=55458
"16/17/18/19 inch rims," 7-pages, JRH
http://endless-sphere.com/forums/viewtopic.php?f=31&t=35442
"Using 17/19 inch moped rims on large hubmotors"
http://endless-sphere.com/forums/viewtopic.php?f=2&t=69104
